The invention relates to a method of detecting a malfunction during a displacement of an element by a drive system. The invention further relates to a device suitable for carrying out such a method.
One known method, which is set forth in EP-B1-0 365 681, detects a collision between machine parts driven by servomotors and an object. A processor calculates the derivative of the speed of the servomotor during a preceding period and subtracts it from the derivative of the speed of the servomotor over the present period. The absolute value of the calculated difference is taken, and this is compared by the processor with a given reference value. If the value is greater than the given reference value, this is interpreted as an indication that there is a collision.
The method of EP-B1-0 365 681 has the disadvantage that the detection of a collision takes a comparatively great amount of time. The great amount of time is caused by the minimum time required for detecting the collision, which is equal to the length of the chosen time period. As a result, a malfunction may already have occurred at the beginning of a period currently being measured.